The pentatonic scales are the most ancient and the most important scales in music. They are approximately 7000 years old and their musical applications are numerous. To the rock, the blues or the jazz guitarist they are essential. One analytic study of these will be of great help concerning both the knowledge of the guitar's arm and the development of the phrasing and general technical improvement. In the book there are five basic positions of the pentatonic scale, which cover the whole amplitude of the fingerboard and twenty exercises on these positions, which have the objective of covering any possible technical problem appearing during the performance of a difficult phrase.